Thursday, July 31, 2014

Brain activity that reflects positive and negative emotion.

Knutson et al. at Stanford note a correlation between self reported positive and negative arousal and fMRI measurement of brain activity in the nucleus accumbens and anterior insula (if you go to Google images and enter these terms you can see the locations of these regions in brain). Their abstract:
Neuroimaging findings are often interpreted in terms of affective experience, but researchers disagree about the advisability or even possibility of such inferences, and few frameworks explicitly link these levels of analysis. Here, we suggest that the spatial and temporal resolution of functional magnetic resonance imaging (fMRI) data could support inferences about affective states. Specifically, we propose that fMRI nucleus accumbens (NAcc) activity is associated with positive arousal, whereas a combination of anterior insula activity and NAcc activity is associated with negative arousal. This framework implies quantifiable and testable inferences about affect from fMRI data, which may ultimately inform predictions about approach and avoidance behavior.
And a figure from their paper:

Meta-analytic results for activity in nucleus accumbens (NAcc; white circles) and anterior insula (black circles) during incentive anticipation. Activation likelihood estimate maps adapted from Bartra et al.  - who also present a list of regions correlating with affect -  superimposed onto the affective circumplex [from right to left: positive minus negative subjective value (SV), positive subjective value, positive plus negative subjective value, and negative subjective value]

Wednesday, July 30, 2014

Brain correlates of behaviors in market bubbles.

Interesting...from Smith et al. a visualization of the part of our brains that seem to be saying "go for it" during a market bubble (and making less money) and another region that is saying "Whoa..." (whose activity is more prominent in successful traders who pull out of the market before the crash.)
Groups of humans routinely misassign value to complex future events, especially in settings involving the exchange of resources. If properly structured, experimental markets can act as excellent probes of human group-level valuation mechanisms during pathological overvaluations—price bubbles. The connection between the behavioral and neural underpinnings of such phenomena has been absent, in part due to a lack of enabling technology. We used a multisubject functional MRI paradigm to measure neural activity in human subjects participating in experimental asset markets in which endogenous price bubbles formed and crashed. Although many ideas exist about how and why such bubbles may form and how to identify them, our experiment provided a window on the connection between neural responses and behavioral acts (buying and selling) that created the bubbles. We show that aggregate neural activity in the nucleus accumbens (NAcc) tracks the price bubble and that NAcc activity aggregated within a market predicts future price changes and crashes. Furthermore, the lowest-earning subjects express a stronger tendency to buy as a function of measured NAcc activity. Conversely, we report a signal in the anterior insular cortex in the highest earners that precedes the impending price peak, is associated with a higher propensity to sell in high earners, and that may represent a neural early warning signal in these subjects. Such markets could be a model system to understand neural and behavior mechanisms in other settings where emergent group-level activity exhibits mistaken belief or valuation.

Tuesday, July 29, 2014

A intriguing take on consciousness as a perceptual construct.

A recent review by Aaron Schurger in Science Magazine pointed me to Michael Graziano's 2013 book "Consciousness and the Social Brain", which I immediately downloaded, read, and abstracted. Very engaging and clear writing (although I am dumbfounded that he makes no reference to Thomas Metzinger's work and 'ego tunnel' model, which has common elements with his own.) In Graziano's theory awareness is information, the brain's simplified, schematic model of the complicated, data-handling process of attention. A brain can use the construct of awareness to model its own attentional state or to model someone else’s attentional state. An extract from Schurger's review:
In Consciousness and the Social Brain, Michael Graziano argues that consciousness is a perceptual construct—the brain attributes it to other people in much the same way that the brain attributes speech to the ventriloquist's puppet. To clarify, imagine being greeted by a very lifelike android version of your best friend with a prerecorded behavioral program that had you genuinely fooled for a few minutes. From your perspective, for those minutes, the android was endowed with consciousness. Thus there need be no truth or falsity to the statement “My friend standing before me is conscious.” Your brain decides that the android–best friend standing in front of you is conscious, and that is what you perceive to be true.
According to Graziano's “attention schema” theory, our own consciousness is also a perceptual construct—a unique one that emerges when the brain applies the same perceptual attribution recursively to itself. We attribute consciousness to others as part of our perceptual model of what they are paying attention to (an inference particularly useful for predicting their behavior). This model describes the process of attention as a mysterious something extra in the brains of beings that are selectively processing information that guides their behavior. When the brain applies the model to itself, “I” become endowed with this extra something as well—although, as with the android, it was never there in the first place.
According to the theory, consciousness is to attention what the body schema is to the body: it is the brain's perceptual description of its own process of attention. The two phenomena are thus locked “in a positive feedback loop,” which explains the tight connection between attention and consciousness. In essence, consciousness is a descriptive story about a real physical phenomenon (attention). The ink in which the story is written (neural activity) is real, and the physical phenomenon that the story is “about” (attention) is real. But, like the talking puppet, the story itself need not be real. We say that we have consciousness, and that it seems irreducible to physical phenomena, because that is how the brain describes the process of attention (in ourselves and in others): as something ineffable.
I'll also give you a clip from my abstracting of the book:
The heart of the theory is that awareness is a schematized, descriptive model of attention. The model is not perfectly accurate, but it is good enough to be useful. It is a rich information set, as rich as a sensory representation. It can be bound to a representation of an object as though it were another sensory attribute like color or motion….the purpose of a model in the brain is to be useful in interacting with the world, not to be accurate.

The body schema and the attention schema may share more than a formal similarity. They may partially overlap. The body schema is an internal model— an organized set of information that represents the shape, structure, and movement of the body, that distinguishes between objects belonging to the body and objects that are foreign.
In the present theory, the attention schema is similar to the body schema. Rather than representing one’s physical body, it models a different aspect of oneself, also a complex dynamical system, the process of attention— the process by which some signals in the brain become enhanced at the expense of others. It is a predictive model of attention, its dynamics, its essential meaning, its potential impact on behavior, what it can and can’t do, what affects it, and how. It is a simulation. The quirky way that attention shifts from place to place, from item to item, its fluctuating intensity, its spatial and temporal dynamics— all of these aspects are incorporated into the model.

Monday, July 28, 2014

Video game puzzle that improves executive function.

Maybe you don't have to pay or a monthly fee for brain exercises to improve your brain's executive functions. An iOS or Android App costing three dollars might do the job. Oei and Patterson make the interesting observation that executive function (making decision in rapidly changing circumstances) can be improved 30% by a video game (Cut the Rope) that requires physics-based puzzle solving but not by an action video game, a fast paced arcade game, or a real-time strategy game. Tests of executive function were administered before and a week after the game training. Their abstract:
Recent research suggests a causal link between action video game playing and enhanced attention and visual-perceptual skills. In contrast, evidence linking action video games and enhanced executive function is equivocal. We investigated whether action and non-action video games enhance executive function. Fifty-five inexperienced video game players played one of four different games: an action video game (Modern Combat), a physics-based puzzle game (Cut the Rope), a real-time strategy game (Starfront Collision), and a fast paced arcade game (Fruit Ninja) for 20 h. Three pre and post training tests of executive function were administered: a random task switching, a flanker, and a response inhibition task (Go/No-go). Only the group that trained on the physics-based puzzle game significantly improved in all three tasks relative to the pre-test. No training-related improvements were seen in other groups. These results suggest that playing a complex puzzle game that demands strategizing, reframing, and planning improves several aspects of executive function.

Friday, July 25, 2014

Life purpose, longevity, and Alzheimers disease.

From Hill and Turiano:
Having a purpose in life has been cited consistently as an indicator of healthy aging for several reasons, including its potential for reducing mortality risk. In the current study, we sought to extend previous findings by examining whether purpose in life promotes longevity across the adult years, using data from the longitudinal Midlife in the United States (MIDUS) sample. Proportional-hazards models demonstrated that purposeful individuals lived longer than their counterparts did during the 14 years after the baseline assessment, even when controlling for other markers of psychological and affective well-being. Moreover, these longevity benefits did not appear to be conditional on the participants’ age, how long they lived during the follow-up period, or whether they had retired from the workforce. In other words, having a purpose in life appears to widely buffer against mortality risk across the adult years.
(MIDUS refers to a longitudinal study of health and well-being that began in 1994–1995. 7,108 participants were recruited from a nationally representative, random-digit-dialing sample of noninstitutionalized adults between the ages of 20 and 75 (mean age = 46.92 years, SD = 12.94)).
An article by Span points to other studies following almost 1,000 people (age 80, on average) for up to seven years, finding that those with high purpose scores were 2.4 times more likely to remain free of Alzheimer’s than those with low scores and also less likely to develop mild cognitive impairment, often a precursor...In a subset of 246 people who died, autopsies found that many of the purposeful subjects also showed the distinctive markers of Alzheimer’s, suggesting that even for people developing the plaques and tangles in their brains, having purpose in life allows them to tolerate them and still maintain their cognition...Another study, of 1,238 people followed for up to five years (average age: 78)found that those with high purpose had roughly half the mortality rate of those with low purpose.

Thursday, July 24, 2014

How do you get to Carnegie Hall?

The standard answer, which I've used to end several of my lectures, is "practice, practice, practice." Macnamara et al. suggest there is a bit more to it than that (like genetics....there's no way my piano sight reading ability, obvious at age 6, was due to practice.):
More than 20 years ago, researchers proposed that individual differences in performance in such domains as music, sports, and games largely reflect individual differences in amount of deliberate practice, which was defined as engagement in structured activities created specifically to improve performance in a domain. This view is a frequent topic of popular-science writing—but is it supported by empirical evidence? To answer this question, we conducted a meta-analysis covering all major domains in which deliberate practice has been investigated. We found that deliberate practice explained 26% of the variance in performance for games, 21% for music, 18% for sports, 4% for education, and less than 1% for professions. We conclude that deliberate practice is important, but not as important as has been argued.

Wednesday, July 23, 2014

Why is melody in the high notes and rhythm in the base?

Hove et al. examine to what extent musical convention might be shaped by evolutionarily-shaped human physiology.
Across cultures, polyphonic music most often conveys melody in higher-pitched sounds and rhythm in lower-pitched sounds. They show that, when two streams of tones are presented simultaneously, the brain better detects timing deviations in the lower-pitched than in the higher-pitched stream and that tapping synchronization to the tones is more influenced by the lower-pitched stream. Furthermore, their modeling reveals that, with simultaneous sounds, superior encoding of timing for lower sounds and of pitch for higher sounds arises early in the auditory pathway in the cochlea of the inner ear. Thus, these musical conventions likely arise from very basic auditory physiology.
The abstract:
The auditory environment typically contains several sound sources that overlap in time, and the auditory system parses the complex sound wave into streams or voices that represent the various sound sources. Music is also often polyphonic. Interestingly, the main melody (spectral/pitch information) is most often carried by the highest-pitched voice, and the rhythm (temporal foundation) is most often laid down by the lowest-pitched voice. Previous work using electroencephalography (EEG) demonstrated that the auditory cortex encodes pitch more robustly in the higher of two simultaneous tones or melodies, and modeling work indicated that this high-voice superiority for pitch originates in the sensory periphery. Here, we investigated the neural basis of carrying rhythmic timing information in lower-pitched voices. We presented simultaneous high-pitched and low-pitched tones in an isochronous stream and occasionally presented either the higher or the lower tone 50 ms earlier than expected, while leaving the other tone at the expected time. EEG recordings revealed that mismatch negativity responses were larger for timing deviants of the lower tones, indicating better timing encoding for lower-pitched compared with higher-pitch tones at the level of auditory cortex. A behavioral motor task revealed that tapping synchronization was more influenced by the lower-pitched stream. Results from a biologically plausible model of the auditory periphery suggest that nonlinear cochlear dynamics contribute to the observed effect. The low-voice superiority effect for encoding timing explains the widespread musical practice of carrying rhythm in bass-ranged instruments and complements previously established high-voice superiority effects for pitch and melody.

Tuesday, July 22, 2014

Blue is warmer than red?

Red colors are arousing, blue colors calming, so at first the results of Ho et al. seem counter-intuitive. A red object at the same temperature as a blue object feels colder, and they suggest that this is because our prior expectation from the red color that it should be warmer biases our perception to make it seem cooler than it is.
It is commonly believed that reddish color induces warm feelings while bluish color induces cold feelings. We, however, demonstrate an opposite effect when the temperature information is acquired by direct touch. Experiment 1 found that a red object, relative to a blue object, raises the lowest temperature required for an object to feel warm, indicating that a blue object is more likely to be judged as warm than a red object of the same physical temperature. Experiment 2 showed that hand colour also affects temperature judgment, with the direction of the effect opposite to object colours. This study provides the first demonstration that colour can modulate temperature judgments when the temperature information is acquired by direct touch. The effects apparently oppose the common conception of red-hot/blue-cold association. We interpret this phenomenon in terms of “Anti-Bayesian” integration, which suggests that the brain integrates direct temperature input with prior expectations about temperature relationship between object and hand in a way that emphasizes the contrast between the two.

Monday, July 21, 2014

Ecstasy (MDMA) and LSD as therapeutic drugs

Kupferschmidt offers two pieces in Science magazine on using two currently banned classes of drugs for therapeutic purposes: the party drug ecstacy (3,4-methylenedioxymethamphetamine, or MDMA), and hallucinogenic compounds derived from fungus or mushrooms (LSD and psilocybin).

NDMA activates brain receptors for dopamine and noradrenaline and releases serotonin from nerve endings, leading to the characteristic feeling of euphoria that made it popular in clubs and at dance events. One study in which 10 out of 12 PTSD patients no longer met the diagnostic criteria for PTSD after two months of taking MDMA has motivated the launching of phase II clinical studies in Israel, Canada, and the United States.

LSD and psilocybin, which bind to serotonin and other brain receptors, are being tested in studies to treat depression, obsessive-compulsive disorder, anxiety, cluster headaches, and nicotine, alcohol, or cocaine addictions.

Friday, July 18, 2014

Feeling the social touch being observed in others.

Interesting work by Bolognini et al. on our mirroring of the emotions of others :
Touch has an emotional and communicative meaning, and it plays a crucial role in social perception and empathy. The intuitive link between others’ somatosensations and our sense of touch becomes ostensible in mirror-touch synesthesia, a condition in which the view of a touch on another person’s body elicits conscious tactile sensations on the observer’s own body. This peculiar phenomenon may implicate normal social mirror mechanisms. Here, we show that mirror-touch interference effects, synesthesia-like sensations, and even phantom touches can be induced in nonsynesthetes by priming the primary somatosensory cortex (SI) directly or indirectly via the posterior parietal cortex. These results were obtained by means of facilitatory paired-pulse transcranial magnetic stimulation (ppTMS) contingent upon the observation of touch. For these vicarious effects, the SI is engaged at 150 ms from the onset of the visual touch. Intriguingly, individual differences in empathic abilities, assessed with the Interpersonal Reactivity Index, drive the activity of the SI when nonsynesthetes witness others’ tactile sensations. This evidence implies that, under normal conditions, touch observation activates the SI below the threshold for perceptual awareness; through the visual-dependent tuning of SI activity by ppTMS, what is seen becomes felt, namely, mirror-touch synesthesia. On a broader perspective, the visual responsivity of the SI may allow an automatic and unconscious transference of the sensation that another person is experiencing onto oneself, and, in turn, the empathic sharing of somatosensations.

Thursday, July 17, 2014

Brain activity can reveal whom someone is thinking about.

A collaboration between five different research centers shows that in predicting or imagining the behavior of others based on their personality the brain relys on the same network of regions that support other forms of mental simulation, such as remembering the past and planning for the future:
The behaviors of other people are often central to envisioning the future. The ability to accurately predict the thoughts and actions of others is essential for successful social interactions, with far-reaching consequences. Despite its importance, little is known about how the brain represents people in order to predict behavior. In this functional magnetic resonance imaging study, participants learned the unique personality of 4 protagonists and imagined how each would behave in different scenarios. The protagonists' personalities were composed of 2 traits: Agreeableness and Extraversion. Which protagonist was being imagined was accurately inferred based solely on activity patterns in the medial prefrontal cortex using multivariate pattern classification, providing novel evidence that brain activity can reveal whom someone is thinking about. Lateral temporal and posterior cingulate cortex discriminated between different degrees of agreeableness and extraversion, respectively. Functional connectivity analysis confirmed that regions associated with trait-processing and individual identities were functionally coupled. Activity during the imagination task, and revealed by functional connectivity, was consistent with the default network. Our results suggest that distinct regions code for personality traits, and that the brain combines these traits to represent individuals. The brain then uses this “personality model” to predict the behavior of others in novel situations.

Wednesday, July 16, 2014

Response of large scale brain networks to acute stress.

I pass on this interesting summary and graphic by Hermans et al.
Exposure to acute stress prompts a reallocation of resources to a salience network, promoting fear and vigilance, at the cost of an executive control network. After stress subsides, resource allocation to these two networks reverses, which normalizes emotional reactivity and enhances higher-order cognitive processes important for long-term survival.

Schematic anatomical overview of salience and executive control networks. The sphere sizes illustrate the relative sizes of the clusters that co-activate with the respective networks. Our model proposes that these two neurocognitive systems are regulated in a time-dependent and reciprocal fashion by stress-related neuromodulators. Adapted from. Abbreviations: AI, anterior insula; am, amygdala; DACC, dorsal anterior cingulate cortex; DLPFC, dorsolateral prefrontal cortex; DMPFC, dorsomedial prefrontal cortex; DPPC, dorsal posterior parietal cortex; FEF, frontal eye fields (precentral/superior frontal sulci); hy, hypothalamus; IT, inferotemporal cortex; mb, midbrain; Th, thalamus; TPJ, temporoparietal junction; vs, ventral striatum.

Tuesday, July 15, 2014

Increased self control without increased willpower

Here is a fascinating bit of work from Magen et. al., who show that a simple cognitive reframing of the classic immediate or delayed gratification test makes energy requiring willpower less necessary.
In our paradigm, instead of presenting choices in a traditional hidden-zero format (e.g., “Would you prefer [A] $5 today OR [B] $10 in a month?”), choices are presented in an explicit-zero format, which references the nonreward consequences of each choice (e.g., “Would you prefer [A] $5 today and $0 in a month OR [B] $0 today and $10 in a month?”). Including future outcomes in all choice options has been argued to reduce the attentional bias toward immediate rewards that contributes to impulsive behavior.
Here, then, is their abstract:
People often exert willpower to choose a more valuable delayed reward over a less valuable immediate reward, but using willpower is taxing and frequently fails. In this research, we demonstrate the ability to enhance self-control (i.e., forgoing smaller immediate rewards in favor of larger delayed rewards) without exerting additional willpower. Using behavioral and neuroimaging data, we show that a reframing of rewards (i) reduced the subjective value of smaller immediate rewards relative to larger delayed rewards, (ii) increased the likelihood of choosing the larger delayed rewards when choosing between two real monetary rewards, (iii) reduced the brain reward responses to immediate rewards in the dorsal and ventral striatum, and (iv) reduced brain activity in the dorsolateral prefrontal cortex (a correlate of willpower) when participants chose the same larger later rewards across the two choice frames. We conclude that reframing can promote self-control while avoiding the need for additional willpower expenditure.

Monday, July 14, 2014

Cooperating with the future

You should have a look at this nice Nature Video that very simply illustrates work by Hauser et al. dealing with how we might design policies aimed at preserving shared resources, such as clean air or fish stocks. They show conditions under which individuals will share current resources with future generations who cannot return the favor. Preservation rather than depletion of a resource for future generations can be obtained if a group of people agrees to a binding vote on how much each member should take from the common pool.
Overexploitation of renewable resources today has a high cost on the welfare of future generations. Unlike in other public goods games, however, future generations cannot reciprocate actions made today. What mechanisms can maintain cooperation with the future? To answer this question, we devise a new experimental paradigm, the ‘Intergenerational Goods Game’. A line-up of successive groups (generations) can each either extract a resource to exhaustion or leave something for the next group. Exhausting the resource maximizes the payoff for the present generation, but leaves all future generations empty-handed. Here we show that the resource is almost always destroyed if extraction decisions are made individually. This failure to cooperate with the future is driven primarily by a minority of individuals who extract far more than what is sustainable. In contrast, when extractions are democratically decided by vote, the resource is consistently sustained. Voting is effective for two reasons. First, it allows a majority of cooperators to restrain defectors. Second, it reassures conditional cooperators that their efforts are not futile. Voting, however, only promotes sustainability if it is binding for all involved. Our results have implications for policy interventions designed to sustain intergenerational public goods.
A variation of this procedure has been put to use by the United States’ largest electric utility, PG&E, to get customers to sign up for monitoring which helps prevent summer electrical grid failure and blackouts by slightly reducing air conditioning when the grid is under stress. Enrollment in the program was enhanced by publicly posting the names of those who had signed up.

Friday, July 11, 2014

Does phase of the moon influence our sleep? Three contradictory studies.

This is an update on a previous MindBlog posting. Vyazovskiy and Foster review three recent studies that give contradictory results on how or whether the phase of the moon influences our sleep. They note that the three studies compared data obtained from different subjects at different lunar phases and were biased and imbalanced in terms of age, gender, and many other factors. They suggest that in future research it should be mandatory to design within-subject experiments, rather than perform further retrospective studies. Here is their statement of the situation:
Whether the moon affects our sleep has intrigued our species since ancient times, but in the last decades only relatively few attempts have been made to address this issue with scientific rigor, and solid conclusions have been elusive [1]. A new cycle of research on the lunar effects on sleep was triggered by a retrospective study which carefully re-analyzed the sleep data collected under laboratory conditions in 33 subjects (age range 20–74 years) and showed clear cut effects of the lunar phase on several subjective and objective sleep parameters [2]. Specifically, EEG slow-wave activity (SWA), total sleep time and subjective sleep quality were reduced around the time of the full moon, while sleep latency and latency to REM sleep were prolonged. This study corroborated an earlier report [5], which found a significant decrease in the amount of subjective sleep around the full moon in 31 subjects (mean age of 50 years). This report triggered two further studies, published in the current issue, which either contradict or report novel effects of lunar phase 3 and 4.
One of these studies, a re-analysis of existing large data sets, could not confirm any of the findings made by Cajochen et al. [3]. By contrast, a second retrospective study [4], in which 47 young volunteers were analyzed, confirmed a decreased total sleep time around the full moon, but REM sleep latency was longer around the new moon. This contradicts the Cajochen et al. study as they found that the latency to REM was longest around the full moon [2].
References: 1. R.G. Foster, T. Roenneberg. Human responses to the geophysical daily, annual and lunar cycles. Curr. Biol., 18 (2008), pp. R784–R794 2. C. Cajochen, S. Altanay-Ekici, M. Munch, S. Frey, V. Knoblauch, A. Wirz-Justice. Evidence that the lunar cycle influences human sleep. Curr. Biol., 23 (2013), pp. 1485–1488 3. M. Cordi, S. Ackermann, F.W. Bes, F. Hartmann, B.N. Konrad, L. Genzel, M. Pawlowski, A. Steiger, H. Schulz, B. Rasch, M. Dresler. Lunar cycle effects on sleep and the file drawer problem. Curr. Biol., 24 (2014), pp. R549–R550 4. M. Smith, I. Croy, K.P. Waye. Human sleep and cortical reactivity are influenced by lunar phase. Curr. Biol., 24 (2014), pp. R551–R552 5. M. Roosli, P. Juni, C. Braun-Fahrlander, M.W. Brinkhof, N. Low, M. Egger. Sleepless night, the moon is bright: longitudinal study of lunar phase and sleep J. Sleep Res., 15 (2006), pp. 149–153

Thursday, July 10, 2014

The untutored mind does not like to be alone with itself.

Our mammalian brains evolved to physically engage the world in the interest of our survival and passing on genes. Humans are distinctive among animals in being able to disengage, and some meditation techniques train just such disengagement. A recent collaboration including Daniel Gilbert (see "A wandering mind is an unhappy mind.") makes the interesting observation that not only is disengagement difficult for most people, some, if asked to just sit in a room and do nothing (with a nine volt battery the only entertainment provided), prefer to electrically shock themselves rather than be deprived of external sensory stimuli!
In 11 studies, we found that participants typically did not enjoy spending 6 to 15 minutes in a room by themselves with nothing to do but think, that they enjoyed doing mundane external activities much more, and that many preferred to administer electric shocks to themselves instead of being left alone with their thoughts. Most people seem to prefer to be doing something rather than nothing, even if that something is negative.

Wednesday, July 09, 2014

Caring for the future

In a fascinating behavioral economics experiment Hauser et al examine willingness of people in a group to sacrifice personal gains for future generations, and show that whether majorities that will sacrifice for the future are adequate for the task depends on whether choices are made individually or by group decision. Nature magazine does a nice presentation of this work with an instructive video and a news and views commentary. Here is the abstract of the article:
Overexploitation of renewable resources today has a high cost on the welfare of future generations. Unlike in other public goods games however, future generations cannot reciprocate actions made today. What mechanisms can maintain cooperation with the future? To answer this question, we devise a new experimental paradigm, the ‘Intergenerational Goods Game’. A line-up of successive groups (generations) can each either extract a resource to exhaustion or leave something for the next group. Exhausting the resource maximizes the payoff for the present generation, but leaves all future generations empty-handed. Here we show that the resource is almost always destroyed if extraction decisions are made individually. This failure to cooperate with the future is driven primarily by a minority of individuals who extract far more than what is sustainable. In contrast, when extractions are democratically decided by vote, the resource is consistently sustained. Voting is effective for two reasons. First, it allows a majority of cooperators to restrain defectors. Second, it reassures conditional cooperators that their efforts are not futile. Voting, however, only promotes sustainability if it is binding for all involved. Our results have implications for policy interventions designed to sustain intergenerational public goods.
And, by the way, here is a nice piece on "Caring for the present", how peer presence and pressure can help preserve electric grids.

Tuesday, July 08, 2014

Information integration without awareness.

I want to point to an excellent review by Christof Koch and colleagues. It contains some useful summary graphics.
•Empirical data suggest that consciousness is not necessary for integration.
•Unconscious integration is nevertheless limited.
•Consciousness enables integrations over extended spatiotemporal windows.
•Consciousness may be needed for novel and high-level semantic integrations.
Information integration and consciousness are closely related, if not interdependent. But, what exactly is the nature of their relation? Which forms of integration require consciousness? Here, we examine the recent experimental literature with respect to perceptual and cognitive integration of spatiotemporal, multisensory, semantic, and novel information. We suggest that, whereas some integrative processes can occur without awareness, their scope is limited to smaller integration windows, to simpler associations, or to ones that were previously acquired consciously. This challenges previous claims that consciousness of some content is necessary for its integration; yet it also suggests that consciousness holds an enabling role in establishing integrative mechanisms that can later operate unconsciously, and in allowing wider-range integration, over bigger semantic, spatiotemporal, and sensory integration windows.

Monday, July 07, 2014

Couch potato? You should be taking omega-3!

I pass on the abstract from Leckie et al. (DHA refers to docosahexaenoic acid, an omega-3 polyunsaturated fatty acid that is highly concentrated in the brain, and has been associated with better performance on measures of executive function.) I guess the idea is that if you don't want to exercise, you should at least take an omega-3 supplement!
Greater amounts of physical activity (PA) and omega-3 fatty acids have both been independently associated with better cognitive performance. Because of the overlapping biological effects of omega-3 fatty acids and PA, fatty acid intake may modify the effects of PA on neurocognitive function. The present study tested this hypothesis by examining whether the ratio of serum omega-6 to omega-3 fatty acid levels would moderate the association between PA and executive and memory functions in 344 participants (Mean age=44.42 years, SD=6.72). The Paffenbarger Physical Activity Questionnaire (PPAQ), serum fatty acid levels, and performance on a standard neuropsychological battery were acquired on all subjects. A principal component analysis reduced the number of cognitive outcomes to three factors: n-back working memory, Trail Making test, and Logical Memory. We found a significant interaction between PA and the ratio of omega-6 to omega-3 fatty acid serum levels on Trail Making performance and n-back performance, such that higher amounts of omega-3 levels offset the deleterious effects of lower amounts of PA. These effects remained significant in a subsample (n=299) controlling for overall dietary fat consumption. There were no significant additive or multiplicative benefits of higher amounts of both omega-3 and PA on cognitive performance. Our results demonstrate that a diet high in omega-3 fatty acids might mitigate the effect of lower levels of PA on cognitive performance. This study illuminates the importance of understanding dietary and PA factors in tandem when exploring their effects on neurocognitive health.

Friday, July 04, 2014

Moral judgements depend on what language we’re speaking.

Costa et al. use the famous trolley problem to offer another example of the incredible power of the tribal or "us versus them" nature of our psychology. Studies have shown that this mentality (fundamental, for example, to the current chaos in the Middle East) emerges spontaneously in previously homogenous groups of young children as well as adults. In the trolley problem, the following scenario is presented to subjects: An approaching trolley is about to kill five people farther down the tracks. The only way to stop it is to push a large man off the footbridge and onto the tracks below. This will save the five people but kill the man. (It will not help if you jump; you are not large enough.) Do you push him? Costa et al. find that when people are presented with the trolley problem in a foreign language, they are more willing to sacrifice one person to save five than when they are presented with the dilemma in their native tongue. Their abstract:
Should you sacrifice one man to save five? Whatever your answer, it should not depend on whether you were asked the question in your native language or a foreign tongue so long as you understood the problem. And yet here we report evidence that people using a foreign language make substantially more utilitarian decisions when faced with such moral dilemmas. We argue that this stems from the reduced emotional response elicited by the foreign language, consequently reducing the impact of intuitive emotional concerns. In general, we suggest that the increased psychological distance of using a foreign language induces utilitarianism. This shows that moral judgments can be heavily affected by an orthogonal property to moral principles, and importantly, one that is relevant to hundreds of millions of individuals on a daily basis.

Thursday, July 03, 2014

Consciousness is constructed through a discrete set of activity spaces.

This fascinating work by Hudson et al. shows that as the brain recovers consciousness from a perturbation such as anesthesia, it does not follows a steady and monotonic path towards consciousness, but rather passes through several discrete activity states. They performed a principal component analysis on local field potentials recorded with electrodes inserted into rat anterior cingulate and retrosplenial cortices and the intralaminar thalamus:
It is not clear how, after a large perturbation, the brain explores the vast space of potential neuronal activity states to recover those compatible with consciousness. Here, we analyze recovery from pharmacologically induced coma to show that neuronal activity en route to consciousness is confined to a low-dimensional subspace. In this subspace, neuronal activity forms discrete metastable states persistent on the scale of minutes. The network of transitions that links these metastable states is structured such that some states form hubs that connect groups of otherwise disconnected states. Although many paths through the network are possible, to ultimately enter the activity state compatible with consciousness, the brain must first pass through these hubs in an orderly fashion. This organization of metastable states, along with dramatic dimensionality reduction, significantly simplifies the task of sampling the parameter space to recover the state consistent with wakefulness on a physiologically relevant timescale.

Wednesday, July 02, 2014

Parenting rewires men's brains.

From Abraham et al., interesting material on a global "parental caregiving" neural network in our brains:
Although contemporary socio-cultural changes dramatically increased fathers' involvement in childrearing, little is known about the brain basis of human fatherhood, its comparability with the maternal brain, and its sensitivity to caregiving experiences. We measured parental brain response to infant stimuli using functional MRI, oxytocin, and parenting behavior in three groups of parents (n = 89) raising their firstborn infant: heterosexual primary-caregiving mothers (PC-Mothers), heterosexual secondary-caregiving fathers (SC-Fathers), and primary-caregiving homosexual fathers (PC-Fathers) rearing infants without maternal involvement. Results revealed that parenting implemented a global “parental caregiving” neural network, mainly consistent across parents, which integrated functioning of two systems: the emotional processing network including subcortical and paralimbic structures associated with vigilance, salience, reward, and motivation, and mentalizing network involving frontopolar-medial-prefrontal and temporo-parietal circuits implicated in social understanding and cognitive empathy. These networks work in concert to imbue infant care with emotional salience, attune with the infant state, and plan adequate parenting. PC-Mothers showed greater activation in emotion processing structures, correlated with oxytocin and parent-infant synchrony, whereas SC-Fathers displayed greater activation in cortical circuits, associated with oxytocin and parenting. PC-Fathers exhibited high amygdala activation similar to PC-Mothers, alongside high activation of superior temporal sulcus (STS) comparable to SC-Fathers, and functional connectivity between amygdala and STS. Among all fathers, time spent in direct childcare was linked with the degree of amygdala-STS connectivity. Findings underscore the common neural basis of maternal and paternal care, chart brain–hormone–behavior pathways that support parenthood, and specify mechanisms of brain malleability with caregiving experiences in human fathers.